Combined atomic force microscope and electron-beam lithography used for the fabrication of variable-coupling quantum dots

TL;DR

This paper presents a novel fabrication approach combining atomic force microscopy and electron-beam lithography to create tunable double quantum dots with enhanced control over interdot coupling.

Contribution

It introduces a combined nanofabrication method enabling precise in-plane and top gate integration on quantum dots for improved tunability.

Findings

Successful fabrication of a double quantum dot device

Demonstrated tunability of interdot coupling

Achieved precise control via integrated gates

Abstract

We have combined direct nanofabrication by local anodic oxidation with conventional electron-beam lithography to produce a parallel double quantum dot based on a GaAs/AlGaAs heterostructure. The combination of both nanolithography methods allows to fabricate robust in-plane gates and Cr/Au top gate electrodes on the same device for optimal controllability. This is illustrated by the tunability of the interdot coupling in our device. We describe our fabrication and alignment scheme in detail and demonstrate the tunability in low-temperature transport measurements.